During medical procedures, endoscopes and other imaging devices are used to perform minimally invasive surgery and diagnostics. These imaging devices typically use a broad band light source to illuminate the tissue inside a cavity so that an image sensor can capture the reflected light and send a signal to a processor for display.
A difficulty with the use of a white light or wide band light source is that hemoglobin absorbs the majority of optical light, and the penetration depth of light is closely related to the absorption spectrum of hemoglobin. In the visible spectrum, hemoglobin shows the highest absorption of blue (˜410-440 nm) and green (˜530-580 nm) wavelength regions. Therefore, optical information obtained in the blue and green spectral region can discriminate hemoglobin concentration an optimal way. Due to the short penetration depth of blue light (˜1 mm), intermediate penetration depth of green light (˜3 mm) and high penetration depth of red light (˜5 mm), the tissue structures near the surface are easily identified, but information in the red spectral region cannot be easily obtained due to the high penetration depth.
There are some known imaging systems that are capable of reducing the contribution of the red light region to a displayed image. For example U.S. Pat. No. 7,420,151 to Fengler et al. discloses a system for performing short wavelength imaging with a broadband illumination source includes an image processor that receives signals from a color image sensor. The image processor reduces the contribution of red illumination light to an image by computing blue, green, and blue-green (cyan) color components of display pixels from the signals received from the image sensor. The blue, green, and cyan color component values are coupled to inputs of a color monitor for display to produce a false-color image of the tissue.
U.S. Pat. No. 4,742,388 to Cooper et al. discloses a color video endoscope system having a light source and a solid state image sensor that transmits a signal to a video processor that converts the signal from the image sensor in to a composite RGB video signal, this RGB signal is received by the video processor and the signal is filtered electronically to vary the color image. Cooper discloses a number of potentiometers that allow the user to select and change red, green and blue gains applied to the signal.
U.S. Pat. No. 6,147,705 to Krauter discloses a video colposcope with a microcomputer having algorithms for color balance. A video camera obtains an electronic image. A CCD sensor converts an image into an analog electrical signal which is amplified and digitized. Using an algorithm-driven digital signal processing circuitry, color saturation, hue and intensity levels of the electronic image are modified according to the DSP reference filter algorithm.
U.S. Pat. No. 7,050,086 to Ozawa discloses a system for displaying a false-color image with reduced red component. The red, green and blue (“RGB”) signals are cyclically and sequentially read from a frame memory, and the frames are used to generate a digital video signal for display. The RGB components are emitted from the distal end face of a light guide and these RGB signals are sequentially and cyclically focused on the light receiving surface of a CCD image sensor. These RGB signals are then sequentially used to update a display or display memory. Optionally, the red component may be reduced by a switching circuit to display a false-color image.
Current systems synchronize the display of wide band and narrow band images. When the wide and narrow band images are both displayed on a monitor using a split screen, or on two monitors, the images are updated at the same time. Further, the required resolution for medical imaging devices may be rather high. Fengler appears to disclose that the wide band and narrow band images can be displayed at the same time, but the processor would need sufficient processing speed to accomplish this task.
Cooper appears to disclose a processor including a series of potentiometers that modify the RGB signal in a way that would allow for the elimination of the red component. These potentiometers allow for an adjustable filter that may be set or checked at the beginning of each procedure
Ozawa appears to disclose cyclically and sequentially reading image signals. However, wide and narrow band display regions are updated at the same time. Thus if one were to display both wide band and narrow band images on a split screen or two separate monitors, both the wide band and narrow band images would be updated simultaneously.
Improved visualization techniques can be used to provide a system that uses less processing power for the same resolution. Likewise, a higher resolution may be obtained with reduced processing power requirements in comparison to prior art systems.
It is therefore an object of the present invention to provide a system for display of wide and narrow band images that uses a cost effective processing technology.
Yet another object of the present invention is to provide an imaging system that can primarily display information obtained from the blue and green wavelength regions that suppresses the red region while reducing the required processing power in comparison to prior art systems.
It is further an object of the present invention to provide an imaging system with sufficient visibility of wide band and narrow band images with reduced hardware costs.
It is yet another object of the present invention to provide a narrow band imaging system that offers simplified settings for display of narrow band images.
It is yet another object of the present invention to provide a system with enhanced resolution without an increase in processing power.